Device and method for positioning an electrode in tissue

ABSTRACT

A device for positioning an electrode in tissue includes: a lead body having a distal portion; an electrode array coupled to the lead distal portion; an anchoring element having an anchor tip and being operable in a first configuration in which the anchor tip is retracted within the lead and in a second configuration in which the anchor tip is extended outside the lead and configured to fixate within the tissue; and a displacement mechanism that is actuated to bias the electrode array or the anchoring element toward the tissue. A method for positioning an electrode in tissue includes: navigating, to the tissue, a lead with an electrode array, an anchoring element with a distal anchor tip, and a displacement mechanism; biasing the electrode array and anchoring element towards the tissue with the displacement mechanism; and deploying the anchoring element, and verifying fixation of the anchor tip within the tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/219,874, filed 29 Aug. 2011 (entitled “Device and Method forPositioning an Electrode in Tissue,” which claims the benefit of U.S.Provisional Application Nos.: 61/387,185, filed 28 Sep. 2010 (entitled“Rhythm Support Device 2”); 61/412,992, filed 12 Nov. 2010 (entitled“Pacing Device”); 61/420,060, filed 6 Dec. 2010 (entitled “PacingDevice”); 61/427,306, filed 27 Dec. 2010 (entitled “Rhythm SupportDevice 5”); 61/445,992, filed 23 Feb. 2011 (entitled “Pacing Device”);and 61/501,450, filed 27 Jun. 2011 (entitled “Pacing Device”). All ofthe above-referenced applications, including each of the six provisionalapplications, are incorporated in their entirety by this reference.

GOVERNMENT LICENSE RIGHTS

This invention was made with Government support under contract TW008781awarded by the National Institutes of Health. The Government has certainrights in this invention.

TECHNICAL FIELD

This invention relates generally to the electrode stimulation devicefield, and more specifically to a new and useful system and method forpositioning an electrode in tissue in the electrode stimulation devicefield.

BACKGROUND

Bradycardia (reduced heart rate) is a common condition affectingmillions of patients annually. Although many such patients requireimplantation of permanent pacemaker devices to help regulate heart rate,other patients experience bradycardia with reversible causes that do notrequire permanent pacemaker implantation and may instead receivetemporary bradycardia support, such as over a period of less than oneweek. One common treatment for temporary bradycardia support involves asystem including transvenous electrode pacing leads that are inserteddirectly into the right ventricle of the heart to stimulate and regulatecardiac function. However, the conventional versions of these systemshave several drawbacks.

Thus, there is a need in the electrode stimulation device field tocreate a new and useful device and method for positioning an electrodein tissue in the electrode stimulation device field. This inventionprovides a new and useful device and method for positioning an electrodein tissue.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of the system of a preferred embodiment;

FIG. 2 is a side view of a distal portion of the system of FIG. 1, shownin a cross-sectional representation of a portion of a heart;

FIG. 3A is a side cross-sectional view of the lead body of the system ofa preferred embodiment;

FIGS. 3B and 3C are end-on cross-sectional views of the lead body ofFIG. 3A, as seen from the perspective of the dotted lines drawn throughFIG. 3A;

FIG. 3D is a side view of a portion of the lead body of FIG. 3A;

FIG. 3E is a side view of a different portion of the lead body of FIG.3A;

FIG. 3F is an end-on cross-sectional view of the lead body of FIG. 3E;

FIGS. 3G and 3H are perspective and side views, respectively, of adistal portion of the lead body of FIG. 3A;

FIGS. 4A and 4B are perspective views of one embodiment of an atraumatictip of the lead body of the system, where FIG. 4A shows the atraumatictip in a collapsed configuration and FIG. 4B shows the atraumatic tip inan expanded configuration;

FIGS. 5A-5C are perspective views of one embodiment of an atraumatic tipof the lead body of the system, where FIG. 5A shows the atraumatic tipin a collapsed configuration, FIG. 5B shows the atraumatic tip in apartially expanded configuration, and FIG. 5C shows the atraumatic tipin a fully expanded configuration;

FIGS. 6A and 6B are perspective views of one embodiment of an atraumatictip of the lead body of the system, where FIG. 6A shows the atraumatictip in a collapsed configuration, and FIG. 6B shows the atraumatic tipin an expanded configuration;

FIGS. 7A-7D are side views of one embodiment of an atraumatic tip of thelead body of the system in various configurations;

FIG. 8 is an exploded view of the handle in the system of a preferredembodiment;

FIGS. 9A-9D are longitudinal cross-sectional views of the handle of FIG.8, illustrating operation of the handle in the system of a preferredembodiment;

FIG. 10A is a perspective view of an alternative embodiment of thehandle in the system of a preferred embodiment;

FIGS. 10B-10E are side cross-sectional views of the handle of FIG. 10A,illustrating operation of the handle;

FIG. 11 is a side cross-sectional view of a distal end of an alternativeembodiment of the handle in the system of a preferred embodiment;

FIGS. 12A-12D are perspective views of the distal end of FIG. 11,illustrating various inner portions of the handle;

FIG. 13A is a perspective view of the system of a preferred embodiment,illustrating one embodiment of a handle of the system;

FIG. 13B is a perspective view of the system of a preferred embodiment,illustrating an alternative embodiment of a handle of the system;

FIGS. 14A-14D are perspective, perspective, side, and side viewschematics, respectively, of a process for assembling the electrodearray in the system of a preferred embodiment;

FIG. 15 is a side view schematic of a variation of the electrode array;

FIGS. 16A and 16B are side view schematics of the anchoring elements inthe first and second configurations, respectively, in the system of apreferred embodiment;

FIGS. 17A-17C are side views of three different variations of theanchoring elements in the system of a preferred embodiment;

FIGS. 18A-18E are side, side, perspective, perspective, and side views,respectively, of an alternative embodiment of anchoring elements in thesystem of a preferred embodiment, illustrating operation of theanchoring elements;

FIGS. 19A-19C are side views of three different variations of theanchoring elements in the system of a preferred embodiment;

FIG. 20A is a side cross-sectional view of a distal end of the lead bodyin the system of a preferred embodiment;

FIGS. 20B and 20C are side views of the anchoring element of the leadbody of FIG. 20A, illustrating movement of the anchoring element;

FIG. 20D is an additional side view of the anchoring element of a leadbody, illustrating movement of the anchoring element, according toanother embodiment;

FIGS. 21A and 21B are side views of a distal portion of the lead body,illustrating verifying anchoring element fixation and electrode arrayposition in the system of a preferred embodiment;

FIGS. 22A and 22B are side views of a distal portion of the lead body,illustrating an alternative embodiment for verifying anchoring elementfixation and electrode array position in the system of a preferredembodiment;

FIG. 23 is a side view of a distal portion of the lead body,illustrating an alternative embodiment for verifying anchoring elementfixation and electrode array position in the system of a preferredembodiment;

FIG. 24 is a side view of a distal portion of the lead body,illustrating an alternative embodiment for verifying anchoring elementfixation and electrode array position in the system of a preferredembodiment;

FIGS. 25A and 25B are end-on and side view schematics, respectively, ofone embodiment of the displacement mechanism arrangement in the systemof a preferred embodiment;

FIGS. 26A-26D are perspective views of a distal portion of the leadbody, illustrating one embodiment of a method of assembling thedisplacement mechanism;

FIGS. 27A and 27B are perspective views of a distal portion of the leadbody, illustrating an alternative embodiment of a method of assemblingthe displacement mechanism;

FIGS. 28A and 28B are perspective and side view schematics,respectively, of an example of the system of a preferred embodiment; and

FIGS. 29A-29F are side view schematics of a distal portion of the systemand a cross-sectional view of a portion of a heart, illustrating themethod of positioning an electrode in tissue of a preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of preferred embodiments of the invention isnot intended to limit the invention to these preferred embodiments, butrather to enable any person skilled in the art to make and use thisinvention.

1. Device for Positioning an Electrode in Tissue

As shown in FIG. 1, the device 100 of a preferred embodiment forpositioning an electrode in tissue includes: an elongate lead body 110having a distal portion 112; an electrode array 150 coupled to thedistal portion of the elongate lead body; an anchoring element 160disposed within the elongate lead body and having a distal anchor tip162, in which the anchoring element 160 is selectively operable in afirst configuration 164 (see FIG. 16A), in which the anchor tip issubstantially retracted within the elongate lead body, and in a secondconfiguration 166 (see FIG. 16B), in which the anchor tip is at leastpartially extended outside the elongate lead body and configured tofixate within the tissue 102 (see FIG. 2); and a displacement mechanism170, coupled to the distal portion 112 of the elongate lead body 110,that is selectively expandable to bias the electrode array 150 and/orthe anchoring element 160 toward the tissue 102. As shown in FIG. 3A,the device 100 may further include an actuator 140 disposed within thelead body 110 and abuttingly engaged with or otherwise coupled to theanchoring element 160 to actuate the anchoring element 160 between thefirst and second configurations. The device 100 may further include ahandle 190 that is coupled to the elongate body 110 and includes a slidecoupled to the actuator with first and second slide positionscorresponding to the first and second configurations of the anchoringelement, respectively.

The device 100 is preferably used to securely place a pacing electrodelead in cardiac tissue, such as for temporary bradycardia support. Thedevice 100 enables reliable implantation and maintenance of the positionof the electrode lead. In particular, as shown in FIG. 2, the elongatebody 110 is preferably navigable through the cardiovascular system (e.g.veins, arteries) into the right ventricle of the heart H, such that whenthe displacement mechanism 170 is expanded, the electrode array 150and/or one or more anchoring elements 160 are biased towards theintraventricular septum. The anchoring elements 160 are configured tofixate within tissue to secure the electrode array 150 in contact withthe intraventricular septum (tissue 102), which the electrode array 150may stimulate to help regulate heart rate. However, the device 100 mayalternatively be used to secure any suitable electrode array in anysuitable tissue. For instance, in one variation (e.g. includes theelectrode array, anchoring elements and a mode of delivery such as acatheter, without including a displacement mechanism), the device 100may be used in applications such as laparoscopic surgery, generalsurgery, spinal surgery, and/or other procedures for any suitabletissue.

1.1 Lead Body

The elongate lead body 110 of the device functions to contain anddeliver the electrode array 150, anchoring element 160, and displacementmechanism 170 to target tissue within the body. The elongate lead body110 is preferably a steerable lead or other elongate body, such as acatheter with a stylet, preformed curve, or other internal steeringsystem. Such steering systems are known by one ordinarily skilled in theart, although the elongate body 110 or lead may include any suitablesteering system for navigating in the cardiovascular system or otherportion of the body. The lead 110 is preferably approximatelycylindrical, but may alternatively be substantially flat or planar, orhave any suitable cross-section. The lead 110 is preferably flexible andmade of a biocompatible material, such as polyurethane or polyimide,although at least some portions may be rigid.

As shown in FIGS. 3A-3H, the lead 110 preferably includes a plurality oflumens that carry control elements (e.g. steering elements, electricalconductors 116 coupled to the electrode array 150, anchoring elements160, actuator 140 coupled to the anchoring elements, and/or fluidchannel coupled to the displacement mechanism 170). At least some ofthese lumens may contain internal tubing, within which a control elementis telescopically disposed. The lumens may be arranged in groups, suchas a first group including at least one lumen 132 for the actuator 140and anchoring element 160, a second group including at least one lumen134 for the conductors 116 (potentially including a ground wire 118),and a third group including at least one lumen 136 for the fluid orother actuator for the displacement mechanism. One or more of the lumensand/or internal tubing may be shaped with keys or other features toprevent rotation of control elements within the lead. For instance, asshown in FIG. 3C, the lumen 132 for the anchoring elements 160 may havean approximately rectangular cross-section to constrain alignment of theanchoring elements in a particular direction.

The first group of lumens passing along the lead preferably includes alumen 132 for the actuator 140. The actuator 140 is preferablylongitudinally translatable within the elongate body and abuttinglyengaged with the anchoring element 160 to actuate the anchoring element160 between the first and second configurations. The actuator 140 ispreferably flexible, to help keep the overall lead body 110 flexible,such as for navigation through tissue and reduced tissue damage. In onevariation, as shown in FIG. 3E, the actuator 140 includes at least aflexible portion that includes a helical cut or groove path 142 passinglongitudinally along and circumferentially around the actuator 140. Forinstance, the actuator may include a wire portion disposed within orotherwise coupled to a tube portion having a helical cut 142. However,the actuator may have a series of circumferential rings, include pleatsor zig-zag cuts, or any suitable cuts and/or other features tocontribute to flexibility of the actuator 140. In another variation, theactuator 140 is additionally and/or alternatively made of mesh orflexible material.

The first group of lumens preferably further includes a lumen 132 forthe anchoring elements 160 extending from, and approximately concentricwith, the lumen 132 for the actuator 140. Between the lumens for theanchoring elements 160 and actuator 140, the lead 110 preferably furtherincludes a sleeve 144 that functions to decouple the anchoring elements160 from rotation of the actuator 140 and/or lead 160. In a preferredvariation, as shown in FIG. 3A, the sleeve is fixed to the anchoringelements 160 and not fixed to the actuator 140, such that the actuator140 is free to rotate independently from the anchoring elements withinthe sleeve 144, and the actuator 140 is free to translate to abuttinglyengage the anchoring elements 160. For instance, an abutting cylinder146 coupled to the distal end of the actuator 140 is preferablyconfigured to push and/or pull the anchoring elements 160 within thelead body 110. Alternatively, the actuator 140 may be fastened to thesleeve and the anchoring element 160 may be not fastened to the sleeve144. In further alternative variations, both the actuator 140 and theanchoring elements 160 may be fastened (FIG. 3D) or unfastened to thesleeve 144, or coupled to the sleeve 144 in any suitable manner. Inanother alternative variation, the actuator 140 may be coupled directlyto the anchoring elements 160 (e.g. crimping, welding) or be integrallyformed from the same piece as the anchoring elements 160. The actuator140 and/or anchoring element 160 may be fastened to the sleeve 144 by asnap lock, such as a ball joint, crimping, fasteners or adhesive.

The second group of lumens preferably includes one or more lumens 134for the conductors 116 that carry a current and/or a ground lead 118.The conductors 116 are preferably wires made of an electricallyconductive material, but may be tubing or another elongate shape. Asshown in FIG. 1, the proximal ends of the conductors 116 are preferablycoupled to generator electrodes 199 and a power source P that areexternal to the patient, and the distal end of the conductors 116 arepreferably coupled to the electrode array 150. In one variation, thedevice 100 may include one current-carrying conductive lead perelectrode in the electrode array 150, such that each electrode can beindividually controlled. In a second variation, at least a portion ofthe current-carrying conductors may be coupled to multiple electrodes.In a third variation, at least a portion of the current-carryingconductors may be coupled directly to an electrode, which is in turncoupled to one or more additional electrodes such that at least aportion of the current-carrying conductors is indirectly coupled to oneor more electrodes. However, the device may include any suitable ratioof conductors to electrodes in the electrode array 150, and in anysuitable arrangement.

The third group of lumens passing along the lead 110 preferably includesone or more lumens 136 for an actuator of the displacement mechanism170. In a preferred variation, the third group of lumens includes alumen or channel that carries a fluid (preferably air) that may be usedto expand the displacement mechanism 170. In this variation, as shown inFIG. 1, the proximal end of the fluid-carrying lumen may be coupled to asyringe or other pump 197 that displaces fluid through thefluid-carrying lumen 136, and the distal end of the fluid-carrying lumenmay be coupled to the displacement mechanism 170. In other variations,the third group of lumens may carry wires, rods, springs or any suitableactuator for the particular kind of displacement mechanism in thedevice.

In a preferred embodiment, as shown in FIGS. 3B-3C, the first group oflumens (including a lumen for housing the actuator 140 and anchoringelements 160) is a central lumen 132 passing approximately axially alongthe lead body 110, and the second and third groups of lumens (housingthe conductors and displacement mechanism actuator) are peripherallumens 134 and 136 that are circumferentially distributed around thecentral lumen 132. Alternatively, as shown in FIG. 3F, the lumen 132 forhousing the actuator and anchoring elements may be off-center, and thesecond and/or third groups of lumens 134 and 136 may be arranged inother off-center lumens. However, any of the groups may be distributed,combined or otherwise arranged in any suitable manner.

As shown in FIG. 1, the lead 110 preferably further includes a distalportion 112 to which the electrode array 150, one or more anchoringelements 160, and one or more displacement mechanisms 170 are coupled.As shown in FIG. 3G, the distal portion defines one or more apertures133 through which the anchoring elements 160 deploy, preferably definingone aperture 133 per anchoring element 160, but alternatively the ratioof apertures 133 to anchoring elements 160 may be less than or greaterthan 1:1. Similarly, the distal portion 112 preferably defines one ormore apertures 135 through which the conductors 116 extend to couple tothe electrode array 150, with one aperture 135 per conductive lead, orwith the ratio of apertures 135 to conductors 116 less than or greaterthan 1:1. Alternatively, the distal portions of the conductors 116 mayremain within the elongate lead body 110, and the electrode array 150 orother interconnects may extend through the apertures 135 into theelongate lead body 110 to couple to the conductors 116. Similarly, thedistal portion 112 preferably defines at least one aperture 137 throughwhich air or another fluid actuates the displacement mechanism 170. Asshown in FIG. 3H, the distal portion 112 or other portions of the lead110 may also include contrast markers 124 made of a material that isvisible under fluoroscopy, such as to aid visual confirmation of deviceposition or placement.

Referring now to FIGS. 4A and 4B, the distal portion 112 of the lead 110preferably further includes an atraumatic tip 114, which functions toreduce or eliminate the likelihood of perforation or other damage to thetissue as the lead is navigated through tissue. The atraumatic tip 114absorbs at least substantially frontal forces (longitudinal force in aproximal direction), and more preferably forces in additionaldirections. The atraumatic tip 114 may include softer, impact-absorbingmaterial such as elastomer with a relatively low durometer, and/or mayinclude geometry to help absorb forces. In a preferred embodiment, asshown in FIGS. 4A and 4B, the atraumatic tip 114 includes a hollowtubular structure. The hollow tubular structure is preferably somewhatnarrow and elongate in a free uncompressed mode (FIG. 4A), relative towhen in a compressed mode (FIG. 4B), such as when the atraumatic tip 114encounters the right ventricle or other tissue). When the atraumatic tipis compressed, the hollow tubular structure preferably flares radiallyand increases surface are potentially in contact the tissue, therebyreducing risk of perforation. The atraumatic tip 114 may additionallyand/or alternatively include one or more features of several variations.In a first class of variations, the atraumatic tip 114 includes otherversions of an expandable tip, such as an expandable cap (“mushroom”shape) as shown in FIGS. 5A and 5B, expandable “umbrella” tines as shownin FIG. 5C, “peeling” tines as shown in FIGS. 6A and 6B or a distalballoon as shown in FIG. 7C. In a second class of variations, theatraumatic tip 114 deforms in a curled manner upon experiencing frontalforces. In one example, as shown in FIG. 7A, the atraumatic tip 114 mayinclude a flexible tip that curls when experiencing frontal forces, andmay further include an internal stylet that helps direct the curling ofthe flexible tip 114 as the tip absorbs force. In another example, asshown in FIG. 7B, the atraumatic tip 114 may include notches that biasthe tip 114 to curl in a particular direction to absorb force. In athird class of variations, as shown in FIG. 7D, the atraumatic tip mayinclude a soft, compressible material and/or have a rounded (e.g.hemispherical) or smooth shape.

The device 110 preferably further includes a handle 190 coupled to thelead body 110. As shown in FIG. 1, the handle 190 is preferably coupledin-line to the lead body 110, such that rotation of the handle 190corresponds to rotation of the lead body 110, although the handle 190may alternatively be coupled to the lead body 110 in any suitablemanner. The handle 190 is preferably a tubular housing that contains theactuator, the conductors, and/or actuator for the displacement mechanism170. As shown in FIGS. 8 and 9A-9D, the overall shape of the handle 190is preferably cylindrical (e.g. somewhat pen-shaped), with a tapereddistal end from which the elongate lead body 110 extends, butalternatively may be a bar-shaped handle, a cross-shape, somewhatplanar, or have any suitable cross-section or overall shape. The handle190 includes a slide 194 coupled to the actuator 140 with first andsecond slide positions corresponding to the first and secondconfigurations of the anchoring element, respectively. As shown in FIG.9A, the handle 190 further includes a trigger release 195 thatselectively engages the slide 194, such that when the trigger release195 is engaged with the slide 194, the slide 194 is constrained in thefirst slide position, thereby keeping the anchoring element 160 in thesecond configuration. In a preferred embodiment, the slide 194 is biased(such as spring-loaded with spring 193) towards the second slideposition, such that when the trigger release is disengaged from theslide 194 (FIG. 9B), the slide 194 is loaded to forcefully travel fromthe first slide position to the second slide position (FIG. 9C), therebydeploying the anchoring element 160 from the lead body 110.Alternatively, when the trigger release is disengaged from the slide194, the slide 194 may be freely movable by the user between the firstand second slide positions. The trigger release 195 is preferably abutton that provides a first stop to prevent slide movement from thefirst slide position to the second position (FIG. 9A) and a second stopto prevent slide movement further distal than the second position (i.e.restrain the slide in the second position as in FIG. 9D). The handle 190preferably further includes a reload switch 196 that retracts the slide194 from the second slide position to the first slide position, therebyretracting the anchoring elements 160 into the lead body 110 (FIG. 9D).

In an alternative embodiment, as shown in FIGS. 10A-10E, the handle maybe a cross-shaped handle 190′ in which the reload switch 196 isdecoupled from the slide 194 such that when the trigger release 195 isdisengaged from the slide 194 (FIG. 10B), the slide 194 is loaded (e.g.,with spring 193) to travel from the first slide position to the secondslide position (FIG. 10C), without effecting corresponding movement ofthe reload switch 196. Similar to the preferred embodiment of the handle190, the reload switch 196 retracts the slide 194 from the second slideposition to the first slide position, thereby retracting the anchoringelements 160 into the lead body 110 (FIG. 10D) and enabling the triggerrelease 195 to reengage with the slide 194 for a repeated deployment ofthe anchoring elements 160 (FIG. 10E). By default, the reload switch 196is in the “ready to reload” position shown in FIGS. 10B and 10C.

Referring now to FIG. 11, the handle 190 may further include a septum198 that reduces likelihood of blood and other fluids from entering thelead body 110 (e.g. through apertures of the anchoring elements 160)when the lead body 110 is placed within the body. The septum 198prevents a pressure gradient between inside the lead body 110 andoutside environment (e.g. right ventricle), such that fluids do nottravel into the lead 110. As shown in FIG. 11, in a preferredembodiment, the septum 198 is coupled to the tapered distal end of thehandle and includes a thin membrane that the slide or actuator (e.g.wire portion of the actuator) can penetrate and travel through withlittle friction during anchoring element deployment and retraction.Alternatively, the septum 198 may be coupled to the inside of the lead110 at any location along the lead 110. The septum 198 is preferablymade of an elastomeric material. However, the septum 198 mayalternatively include any suitable structure and/or material thatprevents a pressure difference between the inside and outside of thelead 110, thereby preventing fluid migration through the lumens of thelead 110.

In some embodiments, the handle 190 is detachable from the lead 110. Forinstance, the handle 190 may be detached after the anchoring elements160 are deployed and the electrode array 150 is fixated in the desiredposition. After the electrical lead 110 has served its purpose and theanchoring elements 160 are ready to be retracted from the tissue, thehandle 190 may be reattached to the lead 110. In these embodiments, thehandle 190 may be a reusable tool that is sterilized and reused withmultiple implantable lead devices (which may be disposable devices),although both the handle 190 and lead 110 may be disposable. In theseembodiments, as shown in FIGS. 12A and 12B, the handle 190 may include acompartment accessible by a hinged cover and enables access to decoupleparticular mechanisms. In a first variation, as shown in FIG. 12C, theactuator 140 is decoupleable from the slide 194, thereby decoupling thelead 110 from the handle 190. In a second variation, the actuator 140 isdecoupleable from the sleeve 144 and/or anchoring element 160, such thatthe handle 190 and actuator 140 may be pulled in a proximal directionaway from the lead 110 to decouple from the lead 110 as shown in FIG.12D, thereby decoupling the lead 110 from the handle 190. However, thehandle 190 may be detachable from the lead 110 in any suitable manner.

As shown in FIG. 1, generator electrodes 199 and the fluid pump 197(e.g. syringe), coupled to the conductors and displacement mechanismactuator, respectively, are preferably located proximal to and alignedwith the handle 190. However, as shown in FIG. 13A, in an alternativeembodiment the generator electrodes 199, fluid pump 197 for thedisplacement mechanism, and/or fluid pump 197′ for contrast fluid arecoupled to the lead body 110 near the handle 190, such as at a junctionwith a Y-connector or other suitable connector. As shown in FIG. 13B,the generator electrodes 199 and/or fluid pumps 197 and 197′ may bedecoupled from the handle 190. For instance, the proximal end of thehandle 190 may include ports that receive generator electrode plugs andfluid supply (e.g. luer lock coupling) for the displacement mechanism170.

1.2 Electrode Array

The electrode array 150 functions to provide a stimulation current totarget tissue. As shown in FIGS. 14B-14D, the electrode array 150preferably includes one or more stimulation electrodes 152 arranged onthe distal portion 112 of the lead body 110. In particular, theelectrodes 152 may be pacing electrodes for temporary support ofbradycardia, but may additionally and/or alternatively be any suitablekind of electrodes. In a preferred embodiment, the electrodes 152 arering or bands arranged serially along the length of the lead body 110,but may additionally and/or alternatively include any suitableelectrodes of other shapes (e.g planar, circular, elliptical) arrangedin any suitable manner. For instance, as shown in FIG. 15, the electrodearray 150 may include an electrode on the distal tip of the lead. In onepreferred embodiment, the electrode array 150 includes two ringelectrodes 152 arranged on the distal portion 112 of the lead body 110.

During manufacture and assembly of the device, the electrodes 152 areplaced in electrical contact with the conductors 116 that carry currentalong the lead body 110. As shown in FIG. 14A, the conductors 116 arepreferably passed along respective lumens within the lead body 110 andextended outside the lead body 110 through respective apertures 135. Theextended ends of the conductors 116 are wrapped circumferentially aroundthe lead body 110, and the ring electrodes 152 are slipped over the leadbody 110 and over the wrapped conductors 116 (FIG. 14B). The electrodes152 may be secured over the wrapped conductors 116 with epoxy orcrimping, and then swaged or otherwise modified until the outer diameterof the ring electrodes 152 is substantially equal to the diameter of thelead body 110, such that the electrodes 152 lie flush with the lead body110. However, the electrode array 150 and the lead 110 may bemanufactured and assembled in any suitable method.

1.3 Anchoring Element

The anchoring elements 160 of the device 100 function to fixate withtissue, thereby securing the electrode array 150 adjacent to targettissue 102. The device 100 may include one or multiple anchoringelements 160, each with an anchoring element body and an anchor tip 162.As shown in FIGS. 16A and 16B, the anchoring elements 160 selectivelyoperate between a first and second configuration, where the anchoringelements 160 are preferably operated in the first configuration 164while the lead 110 is navigated in tissue to the target tissue, and inthe second configuration 166 when the lead 110 is adjacent to the targettissue 102, although the anchoring elements 160 may be operated in anysuitable manner. In one embodiment, the first and second configurationsare “deployed” and “retracted” modes, respectively, of the anchoringelements 160. In the first configuration 164 the anchoring element ispositioned at a first anchoring element position within the lead body110, and the anchor tip 162 is substantially retracted within the leadbody (FIG. 16A). In the second configuration 166, the anchoring element160 is positioned at a second anchoring element position within the leadbody 110 and the anchor tip 162 is at least partially extended outsidethe lead body 110 and configured to fixate within tissue (FIG. 16B). Thesecond anchoring element position is preferably distal to the firstanchoring element position, such that transition from the firstconfiguration to the second configuration corresponds to a distalmovement of the anchoring element 160 (and the actuator 140, which ispreferably coupled to the anchoring elements 160). However, in othervariations the transition from the first configuration to the secondconfiguration may correspond to any other suitable kinds of movement(e.g. proximal, rotational) movement of the anchoring element 160.

The device 100 preferably includes a plurality of anchoring elements160, although in some embodiments the device may include only oneanchoring element 160. In a first variation, the anchoring elements 160are longitudinally aligned, such that the anchor tips 162 deploy inapproximately the same direction (FIGS. 16A and 16B). In a secondvariation, the anchoring elements 160 are laterally aligned andcircumferentially distributed around the lead body 110 (FIG. 17A). In athird variation, the anchoring elements 160 are distributed bothlongitudinally along and circumferentially around the lead body 110,such as in a staggered arrangement (FIG. 17B) or spiral arrangement(FIG. 17C). Furthermore, as shown in FIGS. 18A-18E and 19A-19C, theplurality of anchoring elements 160 may be located along the lead body110 between electrodes 152, alternating with electrodes 152, and/orproximal and distal to electrodes 152 (with electrodes 152 between theanchoring elements 160). In a specific preferred embodiment, the device100 includes two anchoring elements 160 longitudinally aligned with oneanother and located on the distal portion 112 of the lead body 110between the two ring electrodes 152. At least a portion of the anchoringelements 160 may additionally and/or alternatively be coupled to asurface (e.g. outer or underside) of the displacement mechanism 170(FIG. 18E), or on the distal tip of the lead body. However, the device100 may include any suitable number of anchoring elements 160 on anysuitable portion of the lead body 110 and/or displacement mechanism 170or other portion of the device 100, which may depend on the applicationof the device 100.

In an alternative embodiment, one or more anchoring elements 160 mayadditionally and/or alternatively function as an electrode to replace orsupplement the functionality of the electrode array 150. For example, ananchoring element 160 may include an electrically conductive alloy orother material such as tantalum, where the anchoring element 160 iswholly made of, embedded with, or coated with the electricallyconductive material. This alternative embodiment of the device 100 mayinclude various relative positions of anchoring elements 160, electrodes152, and the displacement mechanism 170. For example, as shown in FIG.19A, the lead body 110 may include anchoring elements 160 (functioningas electrodes) proximal and/or distal to the displacement mechanism 170,without additional, separate electrodes 152. As shown in FIGS. 19B and19C, the lead body 110 may include both an anchoring element 160functioning as an electrode, a separate ring electrode 152, and/or ananchoring element on the distal tip of the lead body 110.

The anchor tip 162 of an anchoring element 160 is preferably uncurled inthe first configuration, located within a lumen of the lead body 110. Asshown in FIG. 20A, the anchor tip 162 preferably has a biased cut 168forming a sharpened point, with the bias cut angled such that when theanchor tip 162 is retracted within the lead body 110, the cut issubstantially parallel to the wall of the lumen and may smoothly slidealong the wall to reduce the friction between the anchor tip 162 and thewall of the surrounding lumen and reduce force requirements fordeployment. However, the bias cut may be angled at any suitable angle.In one embodiment, when transitioning to the second configuration, theanchor tip 162 preferably curls upon itself in at least a partial loop(e.g. partially circular loop such as “U”-shaped or “J”-shaped, orpartial loop of other shapes such as triangle or square), such thatafter the sharpened point pierces the tissue, further deployment of theanchoring element results in the anchor tip burrowing and fixating in acurled manner. The curled shape or state helps reduce shifting ordislodgement of the anchor tip 162, in that it is resistant to forces inmany directions. As shown in FIG. 20B, in the second configuration theanchor tip 162 is preferably curled in a circular loop having uniformradius of curvature, although as shown in FIG. 20C, alternatively theradius of curvature may vary (e.g. spiral inwards). The anchor tip 162may curl or bend in such a manner as to cross or overlap with itself.The anchor tip 162 may also bend in such a manner as to trace a paththat returns toward the lead body 110, such as to contact the externalportion of the lead body 110 and/or re-enter the lead body 110.Retraction of the anchoring element 160 after deployment withdraws thecurled anchor tip 162 in a reverse direction in the path that itburrowed during deployment and restores the anchor tip 162 in astraightened shape within the lead body. In a preferred embodiment,uncurled refers to the relative configuration of the anchor tip 162 whensubstantially retracted within the elongate body. Curled refers to therelative configuration of the anchor tip 162 when at least partiallyextended outside the elongate body. The shape of the anchor tip 162 inthe first and second configurations may be of one or more of severalvariations, although it may be any suitable shape. In alternativevariations, as shown in FIG. 20D, the anchor tip 162 may additionallyand/or alternatively include hooks, barbs (e.g. acute bends) or otherfixation features in any suitable shape. Furthermore, the anchor tip 162may include bioresorbable material, such that after a certain amount oftime, the anchor tip 162 dissolves and is absorbed into the body, and/ormay include material that promotes or prevents tissue adhesion. Theanchoring elements 160 are preferably made of nitinol wire or otherbiocompatible shape memory alloy, but may alternatively be formed wireand/or coated with any suitable biocompatible material. In analternative variation, the anchoring elements 160 may be of variablestiffness along the length, such as by allowing gel infusion intoselected portions of the anchoring element 160 or conducting anelectrical signal to electrically-sensitive material to vary rigidity.

The anchoring elements 160 are preferably deployed and retracted, asdescribed above, by spring-loaded or manually controlled longitudinalmovement of the actuator 140 within the lead body 110. However, inanother variation, the anchor tips 162 may be coupled to thedisplacement mechanism 170, such that when the displacement mechanism170 expands, the anchor tips 162 are deployed and fixated within thetissue. In other variations, the anchoring elements 160 may be actuatedwith any suitable mechanism, such as cords. Furthermore, the deploymentand retraction of the anchoring elements 160 may be triggered by amanual action specifically for the anchoring elements 160 (e.g. buttonor slide on the handle 190) and/or automatic means (e.g. triggered byexpansion or unexpansion of the displacement mechanism 170 or based onexistence of electrical contact between the anchoring element 160 andthe electrode array 150).

Anchor tips 162 are finished such that the friction between the anchortip 162 and the material that houses the anchors 160 is reduced so thatthe anchor tips 162 can be delivered with lower force requirements. Oneembodiment is an anchor tip 162 that is finished to have a parallelplane with the inside member that houses anchors 160. This allows theanchor 160 to slide within the anchor housing, while still having asharp corner to pierce through the myocardial tissue. In specificembodiments, the anchors 160 are housed in an inner tube formed from ametal which is disposed in a polymer lead body 110.

The device preferably further includes one or more mechanisms forverifying anchoring element deployment and fixation in tissue, which mayadditionally and/or alternatively be modified for verifying anchoringelement retraction and removal from tissue (such as before removal ofthe lead from the patient). Furthermore, the anchor deploymentverification mechanism may further function to verify the position ofthe electrode array 150 relative to tissue. As shown in FIGS. 21A and21B, in one variation, the anchor deployment verification mechanismincludes a fluid injection port in the lead body that enables release offluoroscopic contrast fluid under fluoroscopy. For example, theapertures from which the anchoring elements deploy may enable contrastfluid 122 to flow out of the lead. When the anchoring elements 160 arenot fixated in tissue, the released contrast fluid will at leastinitially tend to diffuse in approximately the same direction as theanchoring element deployment (FIG. 21A). When the anchoring elements 160are fixated in tissue, the released contrast fluid flow will initiallybe blocked by the tissue and flow away from the tissue (FIG. 22B).Monitoring the flow of contrast fluid and/or using the contrast fluid tovisualize the target environment (e.g., right ventricle) underfluoroscopy aids visual confirmation of anchor tip fixation in tissue102. The contrast fluid injection may be manually controlled such aswith syringe 197′ and/or automatically triggered by another action, suchas deployment of anchoring elements.

Another variation of the anchor deployment verification mechanismincludes an electrical feedback circuit including one or more of theanchoring elements 160 and one or more electrodes 152 in the electrodearray 150. As shown in FIG. 22A, when a deployed anchor tip 162 is notproperly fixated in tissue, contact between the deployed anchor tip 162and a nearby electrode 152 on the lead body 110 triggers a switch on theelectrical feedback circuit that is used to signal the error in anchortip fixation. As shown in FIG. 22B, when the deployed anchor tip 162 isproperly fixated in tissue, the tissue prevents contact between thedeployed anchor tip 162 and the electrode 152 and leaves the switchopen, which is used to signal correct anchor tip fixation.Implementation of this switch to an external electrical system is knownand readily understood by one ordinarily skilled in the art.

As shown in FIG. 23, another variation of the anchor deploymentverification mechanism includes at least two sets of electrical padpairs on the lead body 110, including: a distal pad pair 128 d near andon the same side as the anchoring elements 160 and electrodes 152 andconfigured to contact the tissue, and a proximal pad pair 128 p on anopposite side of the anchoring elements 160 and configured to face awayfrom the tissue. The electrical pad pairs provide outputs of Vd (voltageoutput across the distal pad pair) and Vp (voltage output across theproximal pad pair). When the anchor tips 162 are not properly fixatedand the electrodes are not in contact with the tissue, Vd=Vp(approximately) because both electrical pad pairs are in contact withthe same environment (e.g. blood, but not in contact with tissue). Whenthe anchor tips 162 are properly fixated and the electrodes are incontact with the tissue, Vd>Vp due to the impedance of the tissue incontact with the distal pad pair. The ratio between Vd and Vp (or theabsolute or relative difference between Vd and Vp) can be displayed on areal-time graph, or other display such as an LED display or LCD screen,to the user operating the device in a patient, such that the change inthe ratio results in a change in the displayed signal and, when thesignal difference surpasses a particular threshold, the signal indicatestissue contact with the distal electrical pad pair 128 d, anchor tips162, and electrode array 150.

Another variation of the anchor deployment verification mechanismincludes pressure sensors. In one version, as shown in FIG. 24, apressure sensor 126 is coupled to the lead body 110 and senses when thetissue is in contact when the lead body 110. In other versions, thepressure sensor 126 may be coupled to the anchoring element 160, theelectrode array 150, or any suitable portion of the device 100.Furthermore, although the anchor deployment verification mechanism ispreferably one or more of these variations, the mechanism mayadditionally and/or alternatively be any suitable mechanism.

1.4 Displacement Mechanism

The displacement mechanism 170 functions to bias the electrode array 150and/or anchoring elements 160, or other portion of the lead body 110, ina particular direction, preferably toward the tissue. As shown in FIGS.21-24, the displacement mechanism 170 is preferably coupled at leastpartially circumferentially around the distal portion of the lead body110, and more preferably on at least a side of the lead body oppositethe electrode array 150 and/or anchoring elements 160. The displacementmechanism 170 may additionally and/or alternatively be coupled to thelead body 110 on the same side as the anchoring elements 160 (e.g. theanchoring elements 160 may be coupled to the outer side of thedisplacement mechanism 170), or circumferentially offset from theanchoring elements 160 by approximately 90 degrees (FIG. 25A) or anyother suitable angle. The displacement mechanism 170 may be selectivelyunexpandable to reverse the bias of the electrode array 150 and/oranchoring elements 160, such as after the deployment and fixation of theanchoring elements 160 in the tissue. The device 100 preferably includesone displacement mechanism 170, but may include multiple displacementmechanisms 170 arranged on the lead body 100 in any suitablearrangement; for example, as shown in FIG. 25B, the device may include aproximal displacement mechanism 170 located proximal to the electrodearray 150 and anchoring elements 160, and a distal displacementmechanism 170′ located distal to the electrode array 150 and anchoringelements 160.

The displacement mechanism 170 preferably includes a balloon 172 that isselectively inflatable through a fluid channel in the lead body 100. Theballoon 172 is preferably made of an elastomeric material such assilicon or polyurethane, but may alternatively be made of any suitablematerial. As shown in FIGS. 26A-26D, in a preferred embodiment theballoon 172 may include circumferential bands 174 that slip over thelead 110 and are sealed to couple the balloon 172 to the lead 110. Apreferred method of manufacture of the displacement mechanism 170includes cutting two partially circumferential slits 178 along thelength of a tube 176 (FIG. 26A), folding the central portion between theslits 178 inwards to form two circumferential bands 174 at each end ofthe tube (FIG. 26B), sliding the distal portion of the lead body 110into the circumferential band, and sealing the edges of the tube to thelead body (FIG. 26C). The lead body preferably includes an aperture 137,located underneath with a portion of the balloon 172 that provides airor other fluid to inflate the balloon 172 (FIG. 26D). Alternatively, theballoon 172 may be constructed from sheets. At least two sheets 180 maybe sealed together face-to-face around their periphery to form aninflatable volume that is coupled to the lead body 110 and has anaperture aligned with an aperture in the lead body, such that air orother fluid in the fluid channel in the lead body passes through theapertures of the lead body and inflatable volume to expand theinflatable volume. In a first variation, as shown in FIG. 27A, theinflatable volume is made from rectangular sheets and bonded to atubular band that slips over and couples to the distal portion 112 ofthe lead body, and the tubular band 182 has an aperture that aligns withthe other apertures to enable expansion of the inflatable volume. In asecond variation, as shown in FIG. 27B, the inflatable volume is made ofsheets with one or more extensions 184 (e.g. “I”-shaped, “H-shaped”,“E”-shaped or “L”-shaped sheets) that are wrapped around the lead bodyto form the circumferential bands. In an alternative embodiment, theballoon 172 is an approximately spherical or spheroidal volume, oranother kind of inflatable volume that is coupled to the fluid channelof the lead body.

In alternative variations, the displacement mechanism 170 may be otherexpandable mechanisms, such as an expandable and retractable ring,scaffold, or coil. In some embodiments, the device 100 may furtherinclude a mechanism for verifying displacement mechanism expansionand/or retraction. For instance, the displacement mechanism 170 mayinclude contrast markers to visually aid confirmation of displacementmechanism expansion/retraction under fluoroscopy. In other variations,the mechanism for verifying displacement mechanism expansion/retractionmay be similar to the anchor deployment verification mechanism.

Alternative embodiments of the device 100 may include any combination ofthe variations of the lead body, handle, electrode array, anchoringelement, displacement device, and other mechanisms described above, andmay include additional suitable variations of such mechanisms and othersuitable modifications.

2. Example of an Embodiment of the Device

In an example of an embodiment of the device, the device includes ahandle, an elongate tubular pellethane lead body distally coupled to thehandle and having a distal portion that defines a plurality ofapertures, including two conductive lead apertures, two anchoringelement apertures, and an air aperture. As shown in FIGS. 28A and 28B,coupled to the distal portion of the lead body are: two stimulatingelectrodes suitable for pacing cardiac rhythm, two nitinol anchoringelements with anchor tips that selectively deploy out of the lead bodythrough respective anchoring element apertures, and an inflatableballoon coupled to the lead body on a side opposite the anchoringelement apertures. The lead has an atraumatic tip including soft,compressible material. The two stimulating electrodes are platinum ringelectrodes located approximately 10 mm apart. The two anchoring elementapertures, which are approximately 1.5 mm long, are located between theelectrodes, with the proximal anchoring element aperture locatedapproximately 3.5 mm distal to the proximal electrode, and the distalanchoring element aperture located approximately 3.5 mm distal to theproximal anchoring element aperture. The inflatable balloon, which isapproximately 16.5 mm long and selectively inflatable to bias the distalportion of the lead body in a particular direction toward tissue, ismade from silicon tubing and includes two circumferential bands and acentral portion between the bands. The proximal circumferential band ofthe balloon is approximately 3.5 mm long and is located approximately1.25 mm proximal to the proximal electrode, and includes an aperturefluidically coupled to an air supply. The distal circumferential band ofthe balloon is approximately 3 mm long and located approximately 1.25 mmdistal to the distal electrode. Each anchoring element is made of 0.008in diameter nitinol wire and selectively operates in a retracted modeand in a deployed mode. The anchor tips of the anchoring elements arecoated with a radio-opaque material visualizable under fluoroscopy. Inthe retracted mode, each anchoring element is at a proximal position inthe lead body and the anchor tip is uncurled and sheathed within thelead body. In the deployed mode, each anchoring element is at a distalposition in the lead body and the anchor tip is in a curled loopconfigured to fixate within the tissue.

The lead body defines a plurality of lumens, including a lumen receivingan actuator (stainless steel push wire with an outside diameter of 0.018in and crimped to a stainless steel cylindrical tube with an outsidediameter of 0.025 in and inside diameter of 0.020″) that pushes theanchoring elements in a distal direction to deploy the anchor tips, atleast two lumens each for receiving a conductive lead that extendlaterally outside the lead body and couple to respective ringelectrodes, and a lumen for carrying fluid to inflate the balloon. Theactuator includes a sleeve or collar (stainless steel tube with anoutside diameter of 0.032 in and inside diameter of 0.029 in) that iscoupled to the anchoring elements, but decoupled from the actuator.Additional dimensions of the lead body are shown in FIGS. 28A and 28B.

The handle is pen-shaped and includes a trigger release button that iscoupled to a spring-loaded slide that, when released, transitions theanchoring elements from the retracted mode to the deployed mode. Whenthe trigger release is freed, the slide slides from a proximal slideposition to a distal slide position corresponding to the retracted modeand deployed modes, respectively, of the anchoring elements. Thespring-loaded slide enables the actuator to push the anchoring elementsfrom the proximal position to the distal position, thereby launching theanchor tips into the curled, deployed position. The handle furtherincludes a reload switch that retracts the slide from the second slideposition to the first slide position. The handle is distally removablycoupled to an air supply (syringe) that provides air for inflating theballoon, and further distally removably coupled to generator electrodesthat provide current to the electrodes.

3. Method for Positioning an Electrode in Tissue

As shown in FIGS. 29A-29F, the method 200 for positioning an electrodein tissue in a body includes: navigating, to a location adjacent to thetissue, an elongate lead body with an electrode array, at least oneanchoring element with a distal anchor tip, and a displacement mechanismS210, biasing the electrode array and/or at least one anchoring elementtowards the tissue with the displacement mechanism S220, deploying atleast one anchoring element S230 and allowing the anchor tip to fixatewithin the tissue S240. The method may further include verifyingposition of the electrode array relative to the tissue S250 andverifying fixation of the anchor tip within the tissue S260. In apreferred embodiment, the method 200 is used to provide temporary pacingguidance from pacing electrodes in support of bradycardia, although themethod may alternatively be used in any suitable electrode application.In an alternative embodiment, the method includes the step of biasingthe electrode array and/or at least one anchoring element towards thetissue by deploying at least one anchoring element.

Navigating the lead body to the tissue S210 is a step known to oneordinarily skilled in the art, and may include steps such asmanipulating a handle coupled to the lead, manipulating a stylet, andactivating steering wires. However, any suitable steps may be performed,depending on the exact design of the lead body (e.g. steerable lead,pre-formed curve, stylet) and/or applications of the lead in varyingembodiments. Navigation may utilize fluoroscope, ultrasound, or othervisual modalities. In the preferred embodiment, as shown in FIG. 29A,navigating the lead body includes navigating the lead body through bloodvessels towards the heart.

Biasing the electrode array and/or at least one anchoring elementtowards the tissue S220 functions to encourage direct contact betweenthe electrode array and/or anchoring elements and the tissue, whichimproves fixation of the anchoring element within the tissue. As shownin FIG. 29B, biasing the electrode array preferably includes expandingthe displacement mechanism S222. In a preferred variation, expanding thedisplacement mechanism includes inflating a balloon, such as with asyringe, pump, or manual actuation. The balloon may be on a side of thelead body opposing the anchoring elements such that the balloon pushesagainst a wall opposing the tissue (e.g. wall of the right ventricleopposing the interventricular septum) to displace the lead body (alongwith the electrode array and anchoring elements) towards the tissue. Inother words, expanding the displacement mechanism includes expanding thedisplacement mechanism substantially opposite the direction of anchoringelement deployment. In other alternative variations, biasing theelectrode array and/or at least one anchoring element towards the tissueincludes expanding a ring, scaffold, coil, or other suitable expandingmechanism in any suitable direction.

In some embodiments, as shown in FIG. 29C, biasing the electrode arrayand/or at least one anchoring element towards the tissue additionallyand/or alternatively includes biasing the tissue towards the lead bodyS224. For instance, biasing the tissue towards the lead body may includeapplying suction to pull the tissue towards the lead body (e.g. into theanchoring element apertures or other apertures), or providing pressureon the backside of the tissue (e.g. left ventricle side of theinterventricular septum).

As shown in FIG. 29D, deploying at least one anchoring element S230 andallowing the anchor tip to fixate within the tissue S240 function tosecure the electrode array in contact with the tissue. Deploying theanchoring element preferably includes freeing a trigger release, such asa button or slider, that releases a spring-loaded actuator to actuatethe anchoring elements from the first configuration to the secondconfiguration. However, the actuator may be actuated with a stylet,cords, or any suitable mechanism. Furthermore, in alternativevariations, deploying the anchoring element may include any suitableactuation step that transitions the anchoring element from the firstconfiguration to the second configuration. Allowing the anchor tip tofixate within the tissue preferably includes allowing the anchor tip tocurl into a loop within the tissue, or additionally and/or alternativelyincludes allowing the anchor tip to engage barbs, hooks, or otherfixation features within the tissue.

As shown in FIG. 29E, verifying position of the electrode array relativeto the tissue and verifying fixation of the anchor tip within the tissuefunction to confirm location of the electrode array (and potentiallyother portions of the lead body). These verifying steps may additionallyand/or alternatively function to confirm proper secure deployment of theanchoring elements within the tissue. In a first variation, verifyingsteps S250 and S260 include monitoring location of contrast markerscoupled to at least a portion of the lead body (lead, electrode array,anchoring elements or displacement mechanism) under fluoroscopy, such asmonitoring a display that provides visualization of the contrast markersunder fluoroscopy. In a second variation, as shown in FIG. 29E,verifying steps S250 and S260 include releasing contrast fluid andmonitoring for obstructed path of the contrast flow under fluoroscopy.In a third variation, verifying steps S250 and S260 include receiving anelectrical signal that signifies when the anchoring element is in thesecond configuration and fixated in the tissue. In a fourth variation,verifying steps S250 and S260 include measuring a first electricalmeasure (e.g. voltage, impedance) across a first set of contact pointsintended to be in contact with the tissue, measuring a second electricalmeasure across second contact points intended to not be in contact withthe tissue, and monitoring a comparison between the first and secondelectrical measures. However, any combination of these or other suitableverifying steps may be performed.

As shown in FIG. 29F, the method may further include unexpanding (e.g.,retracting) the displacement mechanism S270 after allowing the anchortip to fixate within the tissue. Unexpanding the displacement mechanismfunctions to substantially restore normal operation of the tissue (e.g.reducing occlusion in the right ventricle while the electrode array iscoupled to the interventricular septum) and/or to enable withdrawal ofthe lead body from the tissue (e.g. through the cardiovascular system).Unexpanding the displacement mechanism preferably includes deflating theballoon displacement mechanism. Deflating the balloon may includewithdrawing fluid from the balloon by suction (e.g. withdrawal of thesyringe, reverse pump or manual actuation), or otherwise releasing fluidfrom the balloon (e.g. allowing a leak), although other embodimentsinclude any suitable reverse actuation performed in expanding thedisplacement mechanism.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

We claim:
 1. A device configured to position an electrode in tissue in abody, comprising: an elongate body having a lumen and a distal portion;an internal tube in the elongate body lumen, said internal tube havingan alignment lumen with a cross-sectional shape; an electrode arraycoupled to the distal portion of the elongate body; an actuator in theelongate body lumen having an anchoring element having a distal anchortip disposed within the alignment lumen of the internal tube, whereinthe actuator is configured to move the anchoring element in thealignment lumen between a first configuration in which the distal anchortip is substantially retracted within the elongate body and a secondconfiguration in which the distal anchoring element is at leastpartially extended outside the elongate body, the distal anchoring tipof the anchoring element being configured to fixate within the tissuewhen in the second configuration, wherein the anchoring element isshaped to be constrained within the alignment lumen to deploy theanchoring tip in an anchor deployment direction; and a displacementmechanism on the distal portion of the elongate body and configured tobias the anchoring element in a direction opposite to the anchordeployment direction.
 2. The device of claim 1, wherein the actuator istelescopically disposed in the elongate body lumen.
 3. The device ofclaim 1, wherein the anchoring element includes a plurality of distalanchor tips coupled to a distal end of the actuator, wherein theplurality of distal anchor tips are axially aligned and configured todeploy laterally in the anchor deployment direction from the elongatebody to fixate in tissue as the actuator is longitudinally advanced inthe elongate body lumen.
 4. The device of claim 3, wherein the pluralityof distal anchor tips are curled and configured to remain straightenedwhile constrained within the internal tube and to curl in a proximaldirection and deploy laterally from the elongate body to fixate intissue as the actuator is distally advanced in the elongate body lumen,wherein the inner tube inhibits the constrained distal tip anchors fromdamaging the elongate body lumen as the anchor element is distallyadvanced.
 5. The device of claim 4, wherein the inner tube is a metaltube.